Automotive friction clutch



Jan. 6, 1953 G, T, RNDOL 2,624,432

AUTOMOTIVE FRICTION CLUTCH Filed July 18, 1946 8 Sheets-Sheet 3 Jan. 6, 1953 G. T. RANDol.

AUTOMOTIVE FRIcTIoN CLUTCH Filed July 18, 1946 8 Sheets- Sheet 4 Jan. 6, 1953 G. T. RAmDoL` 2,624,432

AUTOMOTIVE FRICTION CLUTCH Filed July 18, 1946 8 Sheets-Sheet 5 Jan. 6, 1953 G. T. RANDoL AUTOMOTIVE FRTCTIoN CLUTCH Y 8 Sheets-Sheet 6 Filed July 18, 1946 Jan. 6, 1953 G. T. RANDOI.

AUTOMOTIVE FRICTION CLUTCH 8 Sheets-Sheet '7 Filed July 18, 1946 e n N /E m Jan. 6, 1953 G. T. RANDOI.

AUTOMOTIVE FRICTION CLUTCH 8 Sheets-Sheet 8 Filed July 18, 1946 Patented Jan. 6, 19.53

UNITED ISTATES PATENT GFFI'CE Application July 18, 1946,'Serial No. 684,465

45 Claims. l

The present invention relates to power-operated friction clutch mechanisms, and "more particularly vto correlated functions of personallyoperatable means and torque-responsive `means for controlling the torque-transmittingelements of `such clutches into engagement.

Aprimary object of my invention is toprovide novel automatic vtorque-detection of the initial engaging point of friction clutch torque-'transmitting members upon inauguration of engagement thereof by initial depressing of theaccelerator from engine idling position, irrespective of operational modulation of such initial -point'due to'wear, thermal conditions and vother factors inherently eiective to cause such operational changes in the clutch mechanism.

An object importantly related to the object immediately above is the provision of novel `accelerator control means coordinately cooperative With such automatic torque-detection of the initial point of engagement vtoproduce smoothve- 4hicular acceleration from a standing start through vthe Vfull Vengine operating range of the accelerator into the economy positive-drivefully engaged clutch condition vto simulate the operational characteristics and advantages o'f conventional Huid-drives.

A further important -objectof my invention is to provide novel friction clutch'controlmeans for automotive vehicles whereby substantial accelerator advancingT in an engine accelerating direction is required to inaugurate initialengagement of the clutch mechanism, and 'wherein 'such initial engagement is automatically yeffective vto either arrest or retard further eng-aging action notwithstanding the Yaforesaid advancement of vthe accelerator is halted.

Another important obj ect related 'to the object Ynext above is vthe provision of novel torque-responsive control means for an engageable friction clutch mechanism, to establish said'mechanismin reduced torque transmitting efficiency induced by initial operation of the accelerator.

A further object of the invention is to l,provide improved control means for a friction clutch Which will enable an operator to properly and eilircient-ly control the disengagement of saidclutch and its re-engagement.

Another object is to provide means controlled by the torque initially transmitted by a friction clutch for facilitating its engaging action so as to produce a smooth new of power therethrough under all conditions of operation of the sourcefof power with which said clutch may be associated.

Still another object is to provide means for controlling the engaging of the elements of a friction clutch which is responsive to the torque transmitted by the elements during initial slipping" engagement thereof.

it is an additional and important object of the present invention to provide means for controlling the engagement of a pair of co-rctatable-clutch torque-transmitting elements, `the Vmeans including members Aangularly displaceable upon` being torque initially transmitted by the clutch elements as the same are 'brought into initial slipping eng-agement.

A further object is to embody in a, clutch controlling mechanism, novel means responsive to torque transmitted by the clutch frictional elements `duringv 'initial Aengagement thereof, and made effective to drive the vehicle Vby the operation of -the accelerator mechanism of an engine with which `said clutch Vis associated for controlling the nal engaging operation of said clutch elements aftersad initial contact.

Yet anotherobject is `to provide improved vcontrol means for a friction clutch associated with an internal-combustion'engine having an accelerator mechanism, which `.will control the elements of'the clutch into initially engaged relation directly by torque upon initial actuation of the accelerator mechanism from released engineidling position, and controlled to full engagement by Vthe continued actuation of the accelerator mechanism.

A further object is toA provide vin a control `means for controlling engagement of a lfriction clutch, means `responsive to torque transmitted by the elements of said clutch following their initial engagement for arresting or retardingthe engaging action of said elements.

Yet afurther object is to associate with the arresting or vretarding means of the clutch control mean'sa` manually operated means for controlling vat will the rate of rfinal engaging movement of the clutch elements to fully engaged condition. v

IA further obj ect'is to provide a clutch engaging control means for a frictionclutch associated with an engine, which'will insure that kthe speed of the engine will .always be `maintained atsuch va value in relation to the. torque being transmitted by the clutch elements during engagement that stalling of the engine- Will vbe prevented.

Another object is to so combinea friction clutch control structure with a torque responsive device thattheclutch will be properly controlled without necessity of any adjustment throughout the life of vthe clutch facings in its disengaging and re-eng-aging operations so that a vehicle can be driven eiciently with a minimum of effort and without :likelihood of stalling the engine due to 3 power-operated device having a movable element, which has embodied therein an improved valving mechanism so controllable by a predetermined condition of a device responsive to a predetermined torque transmitted through thel clutch during initial re-engagement, thatV said valving mechanism will be effective 'to-produce smooth engagement of the clutch members irrespective of torque input.

A further object is to associate with a control valve mechanism for a power-operated friction clutch actuating means additional mechanism for personally controlling the movement of the power element of the power-operated deviceV after initial clutch engagement has established the transmission of a predetermined torque therethrough.

A further object is to associate with novel control means employed to control a fluid pressure motor during frictional clutch engagement, an internal-combustion engine accelerator mechanism which will, during its depressing movements, complete the nnal engaging movements of the clutch elements to full operative condition after a predetermined torque is transmitted by the clutch following initial slipping contact of its elements.

A further object is to produce a friction clutch control mechanism which will embody combined coordinated control of a motor vehicle clutch by the use of an accelerator mechanism and a torque-responsive device so associated in their functioning that the initial depressing of the accelerator pedal will initiate rapid engaging movements of the clutch elements to the point of initial contact whereby engine torque is transmitted at a predetermined degree to the driven member of the clutch, but insufficient to drive the vehicle except at a possibly creeping rate of propulsion provided the roadway terrain is substantially level, which condition automatically causes the torque-responsive means to be effective to arrest further engagement of the clutch elements or to retard the rate of engagement so that stalling of the engine will be prevented in the event the throttle opening and resultant speed of the engine are not sufficient to overcome the load imposed in starting the vehicle.

A further object is to produce a friction clutch control mechanism which will embody means responsive to the torque transmitted by the initial engagement of the clutch so as to obtain a smooth final clutch engagement without any special mode of operation of an accelerator mechanism employed to cause clutch disengagement and in-` augurate initial engagement under control of said torque-responsive means, and wherein adjustments to compensate for wear of the various operating parts is entirely eliminated.

A more specic object is to embody in a fric- Y position, and wherein `initial depressing of the accelerator mechanism will inaugurate rapid movement of the clutch elements toward initial contact position which, and upon assuming a condition to transmit a predetermined torque, will accommodate a desirable relationship to be established between continued clutch engagement and engine speed to produce smooth full clutch engagement.

Still another object of the invention is to provide a fluid pressure operated device for operatively disengaging and controlling re-engagement of a vehicle friction clutch, and to control said device in accordance with certain predetermined conditions of the vehicle .engine accelerator mechanism and a torque responsive means.

Other objects of my invention will become apparent from the following description taken in connection with the accompanying drawings showing clutch control structure embodying my invention.

In the drawings:

Figure l is a side View of a portion of a power plant, such as the internal-combustion engine of a motor vehicle, showing my improved clutch control mechanism associated therewith, the clutch being fully disengaged and the accelerator mechanism of the power plant in engine idling (fully released) position;

Figure 2 is'an enlarged view of part of the structure of Figure l showing the accelerator mechanism in a slightly depressed position and the clutch operating fluid motor in a condition wherein the clutch elements are in their initial engaging relation;

Figure 3 is a view similar to Figure 2 showing the clutch elements in their fully engaged relation;

Figure 4 is a side View of the clutch controlling valve mechanism and related control parts mounted on the intake manifold of the engine;

Figure 5 is a plan view of the structure shown in Figure 4;

Figure 6 is a side View similar to Figure 4, but showing the accelerator slightly depressed for causing the carburetor butterfly valve to open for accelerating the engine and conditioning the clutch operating motor as shown in Figure 2;

Figure 7 is a side view similar to Figure 4, but showingY the accelerator pedal in its fully depressed position and the throttle valve of the carburetor in wide open position for conditioning the clutch operating motor so that the clutch is fully engaged as shown in Figure 3;

Figure 8 is a front end View of the control Valve on the engine intake manifold as indicated by the line 8-8 of Figure 4;

Figure 9 is a longitudinal sectional view taken on the line 9--9 of Figure 5;

Figure 10 is a longitudinal sectional View taken on the line Ill-lll of Figure 4;

Figure ll is a fragmentary sectional View showingV the slidable valve element in the same plane as viewed in Figure 9, but operated to the position assumed when the torque controlled solenoid is energized for causing the clutch driving member to be arrested at its initial engaging point;

Figure l2 is a cross-sectional view taken on the .line I2-I2 of Figure 4, showing details of the Aaccelerator pedal controlled solenoid actuated valve in its open position for causing the clutch to be fully disengaged;

Figure 13 is la longitudinal sectional View similar to Figure 10, but showing the position the fra-,impec slidable valve element-assumes to'effect the ini- `tial bleeding off action, corresponding-to Vthe accelerator position shown in Fig. 2, preparatory `to control of the nal engaging movements of the clutch, which latter condition is established immediately following the position shown in Figure 11;

Figure 14 is a sectional view similar to Figure 13, but showing theslidable valve element operated by the accelerator to a position'wherein the final engaging movements vof the clutch elements are completed;

Figure l is a cross-sectional View similar to Figure 12, but showing the solenoid valve in closed position'assumed on initial depressing of the accelerator pedal to inaugurate the clutch engaging control function of the torque-responsive valve mechanism;

Figure 16 is a perspective view `of the slidable valve element;

Figure 17 is a fragmentary sectional view similar to Figure 11, but showing in modified form the lslidable valve element with ailange of such reduced width that it cannot cover'the bleeding off port when the torquecontrolled solenoid is energized, thus enabling the torquecondition of the clutch to slow down theengaging movement of the clutch elements, but not suspend their operation at any 'point of their travelito fully engaged position after the'clutch engaging action has, been inaugurated by initial depressing of the accelerator pedal;

Figure v18 is an end view of the torque-responsive switch unit, said View 'being taken on theline I 8--18 of Figure 1;

Figure 19 is `a cross-sectional view taken on the line I9-i5 of Figure 1 and showing details of the torque-responsive switch and lug driving means;

Figure 20 is a view similar to Figure 19, .but showing the relation of the parts when the engine is driving the vehicle;

tails of the switch elements and the positive clutch lugs associated therewith;

Figure 23 is a perspective View of theengine 'flywheel clutch assembly and the torque-responsive switchactuated thereby, certain parts being shown in section;

Figure 24 is a perspective view of the friction Vclutch assembly carried by the yengine iiywheel and showing detailsof the driven membenreieasing levers, pressure plate and springs associated therewith for engaging the clutch;

Figure 25 is a perspective View of the twoelements of vthe torque-responsive.switch .showing the switch contacts and-.the positive clutch lugs for transmitting the torque load;

Figure 26 is a view of the ignition switch taken as indicated by the line 25-25 of Figurei;

Figure 2'? is a vertical sectional View takenon the line Z'I-Zl of Figurez;

Figure 28 is aninterior View of the ignition switch showing the different fixed contacts;

Figure 29 is a view of the ignition switch movable contact' element Figure 30 is a view of the accelerator pedal operated switch taken on the line ti-tl of AFigure 1;

Figure 3l is a cross-sectional view taken on Athe side of the engine.

the line 3I-3I `ofFigure ,31) showing fdetailso ing cam;

Figure-32-is 1a sectional view taken on the line 32-32 "of Figure 30';

Figure 33.is-a ,fragmentary sectional view similar to Figure 32, but showing the position of the actuating cam whenvthe'movable contact member is'operated to open position which corresponds `to the first dashed line position ofthe accelerator as shown inFigure 1;

Figure 34 is a 'View taken on the line M -340i Figure 32 showing the interior of the switch cover and switch contact members carried thereby; :and

Figure 35 is a schematic view showing details of the electricalcontrol circuits of Figure 1 for controlling the solenoids responsive to operations of the accelerator mechanism and the torque-responsive switch interposed between the vehicle friction clutch driven member and the torque output shaft.

AFigure l, there is disclosed a portion of a motor vehicle (primarily the power plant thereof) havning' associated therewith clutch controlling mechanisrn embodying my invention. The power plant shown as an internal-combustion engine E has associated therewith a friction clutch CL for lconnecting and disconnecting the engine and the change-speed transmission T (partially shown), through which the wheels of the vehicle may be driven at various gear ratios, asis well known practice.

The engine E is arranged to have its speed varied at will by means of a carburetor C and the usual accelerating mechanism, including the pedal P mounted in the operators compartment of the vehicle. The carburetorhas abutterfly throttle Valve I situated in the Venturi passage 2 leading to an intake manifold passage 3 of `the engine. The buttery valve is mounted on a pivoted shaft 4 extending to the exterior of the carburetor housing and on this outer end is an actuating lever 5. Below the lever 5 is a pivot pin 5 lmounted on a bracket BR secured by means of a lateral flange clamped between the carburetor mouting ilange and intake manifold and pivoted on this pin is an L-shaped lever 'l'. One arm t of this lever is operatively connected by a rod 9 to the butterfly valve controlling lever 5 and the other arm l0 of this lever is operably connected to an actuating rod I I eX- tending rearwardly and which, at its rear end, isoperatively connected to an arm I2 of a threearmed lever I3 pivoted 'at any s uitable'pointv on This latter lever is arranged to`be actuated by an accelerator pedal P situated in the operators compartment `and to -accomplish this a-rod i4 is operably connected toan arm I5 of said three-armed lever. The third arm I6 of this lever I3 is employed to controla switch generally indicated by the letters AS which is a part of my improved controlling mechanism and will be later referred toin detail. The acceleratormechanism is arranged to be biased to its released or engine idling position by means of a spring I connected between the engine and the arm I2 of the three-armed lever. This idling position of the accelerator mechanism is determined by means of an adjustable stop I8 comprising a screw cooperating with the buttery valve controlling lever 5. The depressing of the accelerator vpedal from the idling position which is shown in full lines in Figure 1 and Figure 4 will result in opening up of the butterfly valve I of the carburetor and allowing an increased ilow of fuel to the cylinders of the engine to increase the speed of said engine.

Friction clutch construction As best shown in Figures 1, 23 and 24 the clutch CL, which is the 4torque-transmitting friction clutch of the vehicle, is shown as being of a well known design and of the friction type having a single dry disk. This clutch is associated with the flywheel I9 which is secured to the rear end of the engine crank shaft 26 and positioned in the clutch housing 2|. The rear side of this ywheel carries a backing plate 22 upon which is movably mounted a clutch pressure plate or driving member 23. This pressure plate is arranged to be controlled by the usual clutch releasing levers 24 (three in number) pivoted to the pressure plate and the backing plate as shown. Between the backing plate and the pressure plate are a plurality of clutch engaging springs 25 (nine in number). Positioned between the rear finished surface of the flywheel and the pressure plate 23 is the single clutch disk 26 which is the driven member of the clutch. This clutch disk is provided with friction facings 2 and 23 on opposite sides of its peripheral portion. By means of these facings the disk is clamped to the flywheel by the action of the pressure plate under the force of the clutch engaging springs 25. The clutch has a driven or pilot shaft 29, the forward end of which is piloted in the ilywheel by means of a pilot bearing 30. Adjacent the piloted end, the shaft 29 is provided with splines 3| on which is splined for axial floating movement a hub 32. This hub is arranged to have secured to it the previously referred to clutch disk 26 and this is accomplished by means of a flange 33 on the hub, together with cushioning springs 34. The disk 25 is positioned on one side of the flange 33 and a balancing ring 35 is placed on the other side of the flange. The cushioning springs are carried in slots in the flange and registering slots in the clutch disk 26 and the ring 35 also accommodate reception of these springs. The clutch disk 26 and the ring 35 are held in position adjacent the flange 33 by means of rivets 36 which extend through over size openl ings in the ange.

In order that the clutch releasing levers 24 may be operated to withdraw the pressure plate away Vfrom a position clamping the clutch facings between the finished confronting surfaces on the flywheel and the pressure plate and against the action of the clutch engaging springs to thereby release the clutch, there is provided a clutch throw-out bearing 3'| which is mounted for slidable movement on a cylindrical portion 38 of a housing member 33 secured to the forward end wall 40 of the transmission housing 4| which has an integral forwardly extending bell-shaped end portion 42 arranged to be attached to the clutch housing 2| and thus enclose the clutch and the structure between it and the gearing. The cylindrical portion 3B surrounds the pilot shaft rearwardly of the splined end and is spaced slightly from the pilot shaft. A spring 3l acts on the bearing 3T to free it from the levers 24. when the clutch is engaged. The throw-out bearing is arranged to be actuated by a throweout yoke or fork 43 which is secured to a clutch throw-out shaft 44 transversely journaled in the bell-shaped housing 42 below the pilot shaft 29. The outer end of this shaft 44 carries an actuating arm 45 (see Figures 2 and 3) whereby the yoke can be operated from the exterior of the clutch and the bell-shaped portion of the transmission housing to thus disengage the clutch by moving the pressure plate 23 rearwardly.

Clutch actuating motor and control valve therefor In the particular embodiment shown of my improved friction clutch control mechanism I employ, for example, a servomotor of the suction type for disengaging the clutch and for controlling its reengagement. The source of fluid pressure different from atmosphere for operating the servomotor or clutch-actuator is produced, for example, in the intake manifold of the engine. This servomotor is generally indicated by the letter M and is secured to the side of the engine adjacent the clutch by means of a bracket 46 as best shown in Figures 1, 2 and 3. The structure of the servomotor employed comprises two pan-shaped casing members 41 and 48 secured together at the rims of their open sides as by bolts 49. Between these rims is clamped the peripheral portion of a flexible diaphragm 50 providing the movable power element of the servomotor. This diaphragm has operably connected thereto one end of a cable 5| which extends through an enlarged central opening in the wall of the rear pan-shaped member 48 and is arranged to be operably connected by a clevis 52 to an arm 53 pivorted at its upper end to the outside of the clutch housing by a pin 54 (shown in dotted lines in Figures 1, 2 and 3 and in full lines in Figure-35). This arm, at a point intermediate its ends, has operably connected thereto one end of a link 55, the other end of which is operably connected to the upper end of the previously referred to arm 45 employed for actuating the clutch throw-out shaft 44 to which the throw-out yoke is secured. The chamber 56 formed by the servomotor diaphragm 56 and the pan-shaped casing member 41 has mounted therein a spring 51 which normally acts upon the diaphragm to insure that it will be moved to its inoperative position to eliminate tension on the clutch actuating mechanism. The chamber 56 is in communication with a rtube 58 carried on the bottom of the pan-shaped casing 41 and connected to the tubeis a flexible conduit 59 leading to a tube 60 associated with a control valve means forming part of my improved clutch controlling mechanism and which control valve means is generally indicated by the letters CV. Leading from this control valve means CV is a tube 6| arranged to be connected into the intake manifold passage 3 of the engine at a point below the butterfly valve so that the suction of the engine can be caused to be effective in the tube 6I and also in the chamber of the servomotor under cerrtain operating conditions of the control valve means CV.

The control valve means CV is mounted on the bracket BR and the details of said means is best shown in Figures 5 to 16, to which figures reference is now made. The control valve means has a casing 62 bolted to said bracket and in a portion of this casing is a longitudinal bore 63. A passage 64 places this bore in communication with atmosphere through a breather cap` 65. Diametrically opposite this atmospheric passage 64 is a passage 66 leading into a chamber 61 in another portion of the casing to one side of that provided with the bore 63. This chamber 61 ls adjacent a second chamber 68 to which the tube illustrate operated positions wherein the spool valve element and the rod 83 have been moved forwardly relative to the sleeve 9|. When the spool valve element is moved forwardly the forward annular ange 80 will begin to pas-s over the port 18 (Figure 13) and thus enabling air to enter through the port from atmosphere and then now out through the port 11 and passage 66 and thence to the fluid motor M in an apparent manner. The volume of air capable o-f passing through the port 18 can be varied at will by the extent of forward movement of the spool valve element. Figur-e 14 shows `port 18 completely open. The purpose of this permissible continued forward sliding movement of the spo-ol valve element, after port 18 is closed lby energization of solenoid ST, is to accommodate variable bleeding in of air to the servomotor tc thereby control the rate of nal re-engagement movements of the clutch elements, as will be further elaborated upon in connection with the operation of my improved clutch controlling mechanism as a whole.

The rear end of the rod 83. which extends out of the cap 88, is provided with a longitudinal slot 99 in which is mounted a roller |00. The slot 99 is arranged to receive a cam arm which is mounted by means of an integral sleeve |02 on the pin 6, already referred to, and having pivoted thereon the L-shaped lever 1 which forms a part of the mechanical linkage between the accelerator pedal P and the butterfly valve I of the carburetor. The cam arm |0| is rotatably mounted on the pin and is arranged to be moved positively in one direction only by the L-shaped lever. To accomplish this the cam arm |0| carries an eX- tension |03 provided with a laterally extending ange |04 which is arranged to underlie the arm 8 of the L-shaped lever. Thus if there should be rotation of the L-shaped lever in a clockwise direction, as viewed in Figures l and 10 for example, the cam arm |0| will be positively moved with the L-shaped lever 1 and the connected accelerator mechanism linkage.

The cam arm |0| is so constructed and positioned with respect to the rear end of the rod 83 that when the solenoid ST is de-energized with the rod 83, together with the spool valve element, is at the extreme rearward position as shown in Figures 9 and 10, the end of the rod will lie beneath a pin carried on the side of the cam arm so that this Icam arm cannot be rotated while the rod 83 is so positioned. However, if the solenoid should be energized and the spool valve element, together with the rod 83, are movedforwardly to the positions shown in Figure 11, then the end of the rod will be moved from beneath the pin |05 so that the cam arm is free -to be rotated and moved through the end of the slot 99 beyond the roller, as is illustrated in Figures 13 and I4. In all axial positions of the rod 83, as shown in Figures -14 inclusively, the cam arm extends slightly into the roller slot to thus prevent turning of rod 83 and the spool valve element.

The movement of the cam -arm |0| is accomplished by the depressing of the accelerator pedal to open the butterfly valve, and the mechanical connection between the cam arm and the accelerator mechanism is accomplished by means of a torsional spring |08, one end of which is hooked over the arm 8 of the L-shaped lever and the other end of which is hooked over the pin |05 on the side of the cam arm, With this torsional spring it is possible for the cam arm to be preventedfro'ni movement by th'eeng'agement of pin |05 with the end of rod 83, yet the accelerator mechanism.V can be actuated relatively so as to open the butteriiy valve of the carburetor. The torsional spring arrangement also insures that as the buttery valve is opened by the accelerator mechanism, a greater stored up energy will be placed in the spring to cause rotation of the cam arm whenever it is freed for operation as a result of the rod 83 being moved initially forwardly.

The cam arm is employed to actuate the spool valve element 19 independently of any actuation thereof by the solenoid, and this separate actuation is -controlled by cam surfaces |01 and |08 on the outer edge of the cam arm. The cam surfa-ce |01, which is adapted to operate first upon the roller |00 to move the rod 83, is eccentric with respect to the pivotal axis of the cam arm, whereas the cam surface |08, which also acts on the roller |00 following that of cam surface |01 is Y concentric with respect to the axis of the cam arm. With such an arrangement it is therefore possible to actuate the rod 83 and the spool valve element by the cam arm only when the cam surface |01 is cooperating with the roller |00. This cam surface |01 is shown to -be operative upon the roller |00 for approximately thirty to forty percent of the full permissible travel of the cam arm, which permissible travel corresponds to the travel of the L-shaped lever 1 of the accelerator mechanism when said accelerator mechanism is moved from its released position to its full throttle open position.

' The tension of the torsional spring |06 bears a direct relationship to the tension of the spring 91 positioned within the sleeve 9| and which latter spring must be overcome t0 move the spool valve element forwardly relative to the sleeve 9| after the solenoid ST has been energized. The torsional spring |0B is not strong enough to move the spool valve element against spring 91 when in its normal pre-tensioned condition; that is, the condition existing when the flange |04 on the eX- tension of the cam arm is in engagement with the arm 8 of the L-shaped lever, as would be the case when the accelerator pedal is fully released in engine idling position. Thus, even though the solenoid may be energized and the roller end of the rod 83 moved from a locking position beneath the pin of the cam arm, there will be no forward movement of the rod 83 and the spool valve element by the cam surface |01 acting on the roller |00 until the torsional spring |06 is given a tension greater than its normal tension. This greater tension will be accomplished by operation of the accelerator mechanism in a direction to open up the butterny valve and speed up the engine. A suiiicient tension will be obtained to cause the cam arm to rotate and move the spool valve element forwardly when the accelerator has been depressed about thirty to forty percent of its full permissible travel to cause full butterily valve open position. When the torsional spring is suiciently tensioned to operate the rod 83 and the spool valve element, the operation will be slow due to the contour of the cam surface |01 and consequently the spool valve element will have a slow forward movement which is -that desired to accomplish the proper bleeding in of air under atmospheric pressure to the fluid motor M to obtain smooth clutch engagement.

Torque-controlled device The solenoid ST, which operates the slidable spool valve element, is adapted to be energized only after a predetermined torque has been engagea.

I3.' transmitted-by the initial engaging.. of the clutch members or elements, which torque while normally. insufficient to drive the vehicle fromA a standstill except possibly ata creeping rate; of propulsion may be adjusted to...hold the vehicle froma roll-back on upgradesv aswill hereinafter be.fully explained. This. predetermined. torque is-selected to occur upon initial torque` transferring contact ofthe clutch faces with the. pressurel plate.Y andthe flywheel surface. To accomplish. this novel clutchy controlling operation, I`- have. provided a specially designed torque-controlled. deviceA shownby way of example, as a switch Whichis generally indicated. by theY letters 'TS.y andfis interposed `between the. driven member; 2.6 andv shaft |09. of the clutch CL. This clutch. driven. or transmission. driving shaft |09 is mounted in theciorward end wall Mlof. the. trans.- missionhousing 4I by. means. of a bearing. I I0.;

The.- rear end of. theshaft. I09 carries. the usual.

transmission driving gear III which Vis inconstant.: meshV witha countershaft gear' |12,I as. is;

the well known arrangement. Also inthe trans.- xnissionthere. is the driven shaft I|3,(Figure 1) and fthe `usual change-speed controlling gearsets.y

and clutches on thisdriven shaftand countershaft,.further details of which` arevv not shown, nor described since they constitute no, part of the present invention.

The torque-controlled switch TS is shown in detail in Figures 1'9 to Z3 and 2.5 and .reference isfnow.- madev to these` various figures. The rear end of-the driven member,l shaft 2.9L. is provided with `an.armular flange. IIA: and the. forward end.

of; the, drivenshaft |Il9-has splined; thereongfor rotationr therewith an annular; confronting member; ||5. In order that these two driven. shafts; may, be maintained inV proper alignment, the rear end, of v the shaft 29 is provided. with,V a reduced4v extension IIS which is piloted; inthe forward end of the driven shaft |09, asbest shown:

in, Figure 22. The flange IId onthe` shaft: 29 isv provided with two. pair of axially projecting; driving. lugs II'I and IIS and arranged to be positioned between each pair of these lugs is a1 larger. driving lug ||9 extending from the-memb er ||5 on the driven shaft |09. LugA |I9zis1of less, width than the distance between the lugsv and IIB. to providev predetermined. relative movementy between the shaft 29 and,` the'driven shaft. |09. in either direction of rotation. In. order-,that each lug I I9 may be centered between thelugs; III and ||8 so that there willbe the samepredetermined relative movement `i-n either direction from. said centered clutch-disengagedV position-there is provided, for exam-ple, on.l the shaft. 2S.. two torque yielding pre-energized leaf springs |A and |.2|, said. springs being. securedV tothe shaftl by rivet pins |22, as can bestbe. seen in` Figures i9 to 2l. The corresponding ends ofv theseleaf springs are spaced apart and receivedv between each pair of spaced ends isa lug ,|2'3 carried by and extending axially from the, member IIT, on the driven shaft. |09 in av the clutch from the engine it is see from Figurel 20- thatonev end. of the, leaf spring.V |20k and theopposite-end; ofthe leaf spring., |2,I: willyield contacts;- Iig and. |21.

until` the.` driving lug, lila'. engages the. driving lug IJIS. If;the.driven.shaft it-.leadinaito the transmissionshould become the. driving mem.- ber, a.: conditionwhich `would occur, for example. in .coasting; drive. during .shifting from a higher speedi'to a lower speed indescending a. grade with;the ,vehicle, .then the other ends o-f theleaf springs; would? yield asthe clutch engages until therevvtluidV be a driving condition'. existing between,y the.;h1.gs IIS); andthelugs. I'I'i, as is illustrat-.edin- Figure 2:1..

The; transmittable torque necessary to additionallly stressthe leaf Springs as accommodated. b-yf-thev relative movement between the shafts 29, |09..` isemployed to close a switch which forms part of.. the-electricalcircuit for energizingA the solenoid SI-, already referred to. This switch comprises an. insulative ring |24 secured, as. by pinning, cntheperiphery of the flange |54V of the driven member shaft 29 and embeddedA in this insulative material is a collector ring I of conducting material. On diametrically opposite. sides; ofthe collector ring there projects axiadlyfa .pairzof` integral. circumferentially spaced In ar. somewhat simi-lar.'

" manne-rpthe member; lili, splined on the: forward end of.- the; shaft |09; has.. secured. thereto.,

bypinning.: a: ring; of insulative material mi' in vvhichfis. embedded a collector ring |29; of. con.- ducting; material and; axially projecting from, diametrically opposite sides ofgthe col-lector ring arefsinglecontacts |30; each; of which is arranged.

toi; lier betweeny andgbe. out of Contact withA spaced contactsy |26 and |21 onthe collector-'ringy car;-

. riedf by the: shaft 29; when the. torque yielding leaf' springsV are not additionally stressed or loaded.- by atransmission of torque as bestv shownv in Figures I9- and 23. It is important to note hereV that the weight o-f the torque-springs |20r-I2 I' determines` the amount of torque transmittable by the clutch frictionalmembers in partially engaged. slipping condition, during ther limited relativev movement of the clutch driven. member Ziiand the driven shaft. IAM-'to actuate the torque-device TS to establish the clutch. membersv in., saidv drive slipping condition;

As best shown, in..1"igure 23, thecollector ringu |25 has -riding thereon a brush |3| carried by the previouslyreferredto housing 39 secured` to the forwardend Wall 40 ofthe transmision housing as by cap bolts. In a like'manner the collec-- tor ring |29 has riding thereon a brush |322,v alsoV carried by. said. housing 39. These two brushes are providedrespectively with terminals |33- and- I34. As best shown in-.Figures 1 and 23 and the wiring diagram in Figure 35 invwhich latter View energizedcircuits:areshown in solid lines and deenergized circuits indash lines, the terminal |33 is. connected by an. electrical conductor |35 with oneV terminal. |36 of the 'winding of the solenoidv STT already referred to. The other terminal |31 of this windingv ofthe solenoid is. connected by a. conductor |38 with ground. The terminal |34 y forthe brush |32 is connected by a conductor |39- directly with an ignition switch, generally indicatedvby the. lettersfIS and to be later referred to in detail.. This ignition switch controls theelectrical circuit of the vehicle, as is well known, there being-a conductor coming to the switch. from. a grounded* battery .B.

It isfseen from'theforegoing that the torsional switch TS,y comprising the spaced contacts I 26. and |21 carriedby the shaft 29 and the contacts |30 carried. bythe driven shaft |09, together with thetorque yieldingileaf springs-controls theen.-

ergization of the solenoid ST. Whenever contacts |30 engage contacts |26 the circuit will be closed. This will occur only when the torque being transmitted is such as to cause yielding of the leaf spring and sufficient relative movement between the driven shafts 29 and |09 to bring the contacts |30 into engagement with the contacts |26 as shown in Figure 20. A similar closing of the circuit will occur when the contacts |21 and |35 are engaged, as would happen under certain conditions where the clutch is being engaged with the vehicle wheels as the torque source. The engaged condition of contacts |21 and |30 is shown in Figure 2l. Wheneverthe circuit for the solenoid ST is established by required torque transmitting conditions, the spool valve will be moved immediately to the position shown in Figure 11, thus cutting oi all communication between the atmosphere and the suction motor M.

Accelerator-controlled switch As already previously mentioned the solenoid SR, which controls the double acting valve element for causing clutch disengaging operation by the servomotor M and the controlling of the initial and final re-engaging stages of said clutch is under the control of the accelerator mechanism. This control is accomplished by means of an accelerator-controlled switch AS which is mounted on the rewall |4 as is shown in Figure l. The details of this accelertaor controlled switch AS are shown in Figures 32 to 34 and reference thereto is now made. The switch has an open sided box |42 secured to the rewall by bolts |43. The open side of the box is closed by a cover plate |44 made of suitable insulative material. This cover carries an extension |45 of conducting material upon which is pivoted a movable contact element |46 for cooperation with a xed contact |41, also carried by the cover- A suitable spring |48 normally biases the movable contact into engagement with the xed contact. The extension |45 is connected to an external terminal member |49 and a conductor |50 leads from this terminal member to the terminal |5| from the solenoid SR. The other terminal |52 of this solenoid is connected by a conductor |53 with a suitable ground such as the engine of a vehicle. The fixed contact member |41 of the switch AS has a terminal |54 which is connected by a conductor |55 to an ignition switch IS to be controlled thereby.

The switch AS, as already mentioned, is to be controlled by the accelerator mechanism and to accomplish this the switch box has mounted therein a shaft i 56 which is provided with a cam surface |51 for cooperation with an insulated extension |58 of the movable contact |56. By means of the cam and the extension the movable contact can be moved from its closed position against the bias of its closing spring to open position. On the outer end of the shaft |56 is secured an arm |59 and a link |60 operably connects this arm to the third arm |6 of the threearmed lever I3 forming a part of the accelerator mechanism linkage between the accelerator pedal P and the butterfly valve I of the carburetor. The connection between the accelerator mechanism and the switch AS is so arranged that when the accelerator pedal P is in its fully released position (idling condition of the engine) the movable contact |46 will engage the fixed contact |61 and the switch AS will be closed, thus energizing l the circuit for the solenoid SR and causing this solenoid to be operative to move the valve element 10 olf from the seat 14 and onto the seat 69 so that the servomotor M can be directly connected with the intake manifold of the engine. This will cause operation of the servo-mechanism M and result in the full disengagement of the clutch. When the accelerator mechanism is operated from its released position by a slight depressing of the accelerator pedal and before any appreciable speedup of the engine occurs, the connection between the accelerator mechanism and the switch AS will cause an opening of the switch, that is, a disengagement of the movable Contact |46 from the fixed Contact |41. This will break the circuit for the solenoid SR and the plunger thereof will then be moved by spring 13 so that the double acting valve element 19 will be placed in the position shown in Figure 15 which will result in the servomotor being disconnected from the intake manifold and connected through the chambers 61, passages 65 and 64 to atmosphere to accommodate the flow of air from atmosphere from the servomotor to be under the control of the spool Valve element 19 already described. The switch'AS remains open under all operative conditions of the accelerator mechanism and is only closed when the pedal of the accelerator mechanism is in fully released (engine idling) position.

Ignition switch The ignition switch IS is of well known construction and is illustrated in detail in Figures 26 to 29. This switch IS is mounted on the instrument panel |6| in the drivers compartment of the vehicle, as probably best illustrated in Figure l. The ignition switch has a casing element |62 secured to the instrument panel and is provided on its back surface with an insulative panel |63. This insulative panel is provided with three fixed contacts |64, |65 and |66. The contact |64 is provided with a terminal |61 to which the conductor |40, already referred to and coming from the battery B, is connected. The fixed contact |65 is provided with terminal |68 to which a conductor |69 lea-ds to the ignition coil and other units comprising the ignition system of the engine (not shown). The third xed contact |66 is provided with terminal |10 to which the two pre-` viouslyl referred to conductors |39 and |55 are connected, the former coming from the brush |34 of the torque switch TS, already described,

and interposed between the engine friction clutch and the change-speed transmission, said switch TS forming a part of the circuit of the solenoid SR already described. Within the switch box s a triangular shaped movable block of insulative material |1| which is secured at the upper corner by a pivot pin |12 extending through a closure plate |13 and having mounted on its exposed end the ignition switch actuating lever or button |14 accessible to the operator of the Vehicle. The block of insulative material |1| carries a triangular shaped plate |15 of conducting material having three extruded contact buttons |16, |11 and |18 for cooperation with the fixed contacts |64, |65 and |66, respectively. The contact button |15 is arranged to be in constant engagement with the xed contact |64, whereas the contact buttons |11 and |18 are arranged to be movable simultaneously onto the contacts |65 and |66 or out of engagement therewith. The springs |19 interposed between the plate |16 and the block |1| biases the buttons into a position for making proper contact. nected at its center to the block by a pin |80.

The button plate |16 is conesegesi 17 The block also carriesa pin |8| movable in a slot |82 of the plate' |13 forlimiting the swing'- ing movement ofthe block and the button carrying plate to provide a` denite open and closed condition of the switch contacts. When the ignition switch isr closed; that is, the lever |14 turned to a position wherein the contact buttons and r|78 engage, respectively, the Xed contacts |65 and |66, the ignition switch willA be closed so that electrical energyfrom the battery can flow to the ignition circuit and -to thecircuits of the clutch control mechanism, provided said circuits are in closed condition.'A The closed position of the ignition plate |16l is shown by full lines in Figure 28. When the` insulating block Iii and the platell are swung tothedctted line shown in Figure 28 the ignition switch will be open. A

Referring to the operation of my improved clutch control mechanism, let it first be assumed that the accelerator pedal P is fully released'so that the butterfly Vvalve of the carburetor C is in its closed idling position `oi the engine.V

When this switch AS is closed, the solenoid SVR will be energized and the double acting valve element 'It thereof will be actuated to the position shown lin Figure l2 Awhich will result 'in the chamber 56 of the servomotor being placed in direct communication withthe intake Vmanifold of the engine. Differential fluid pressurewill then be eective on the movable diaphragm 50 of the servo-mechanism to cause it'to bey moved to the position shown in Figure 1, thereby moving the pressure plate 23` of the friction clutch CL rearwardly by the connecting linkage and releasing or opening the' clutch so that' no power can be transmitted therethrough from the engine. When the accelerator mechanism is released the solenoid ST will not be energized and, therefore, the spool valve element 19 will be inv the' position shown in Figures 9 and 10 which position will admit air under atmospheric pressure to the chamber 61, butl which cannot o'w therefrom to the fluid-pressure motor M dueto the valve 1e being seated on the valve seat B9; The reason that the solenoid ST is not energized is because the torque-responsive switch TS, interposed between the clutch and the change-speed gearing, is not closed to cause energization of the solenoid circuit. The torque responsive switch 'IS is open because no torque is being transmitted therethrough (clutch CL disengaged) and, therefore, thev torque yielding leaf springs maintain a normal relationship between the clutch shafts 29 and |09 which insures that the torque switch contacting elements will beopen as illustrated in Figure 19.

If it should now be desired to refengage the clutch CL, as for example when starting the vehicle from a stopped position with aY low speed drive established or'after changing a gear yratio of the gearing when the vehicle is moving, all that needs to be done"V is to depress the accelerator pedal P. The initial Ydepressing of Ythis accelerator pedal will cause theacceleratorswitch AS to be opened. Upon opening of the switch AS .the solenoid SR'will be immediately deeenergized'and the i spring '|3` acting, onv the plunger `72; thereof will also immediately placethe= double acting valve element in the, position shown in Figure whereby lthe suction present' in the intake manifold will'be cut oir frori the fluid motor M.

- Simultaneously with the cutting oiof the source of suction, the fluid motor will be connected to atmosphere due to th`uns`eatii1g of the element 7G' from the seat 69. This V'connection to atmosphere from the fluid motor will then be through the conduit 59', tube Eli, Chamber E58, chamber 6l, passage B, port "il, port i8,V passage Se and through the breatherV cap |55, the spool valve element' still remaining in the position shown in "Figures Qand 10. The rate of flow of air under atmospheric'pressure to the fluid motor M will be controlled Vby the cross-sectional area of the port '1S'. "As air Aunder atmospheric'presslure enters the chamber ofthe fluid'rnotor, the differential fiuidpre'ss'ures acting on the" diaphragm ofthe'uid 'ni'tirwill'len to equalize and consequently' the diaphagm'will be moved to the right as vViewed Figure' l, thus releasing the clutch engaging springs 25 `to 'expand yand move the pressure plat'e2'3l in adirctioii to cause initial Clamping-of the Cltchfa'ings 2.7 and 23 between Said pressure plateV and the' clutching finished Surface of the engine` flywheel.' U"llii's reengaging' action ofthe clutch will continue inthe aforesaid mannervv irrespectivdof theeiiteht of operating the accelerator 'pedal in an engine a'eceier'atmg direction iitu initial" engagement of the. Clutch iS' eaclied.m During" the depressing of theY pedal of the'aoceleratorinechanisrn fospe'ecling up the engine, the'spoolvalve' element 19 will not be moved since'the'ca'm arm lo] is'preve'nted from being I'no've'd by.v the operation'off the accelerator VIiiec'l'lariisiil,` due" totlieffact that the roller eIIdOf the 'dd 83' isl udeil'the pin m5 car- Tied VbyV the earn ai'i.' v'Ifhe la'ccelerator mechanism vis free to be moved' l'io'wever,v dueto the interpostiori of'tlie`to1sional'-spring |65 between the Lshaped lever Tof the accelerator linkage and the cam arm |01. ThisA movement of the accelerator mechanism does :nothing more than'a'ccelerate the engine with attendant increase in the tension of thetorsional'spring"- As' the clutch is'operat'e'dtoward fully engaged condition,`there will first occur an initial clamping Yaction of the" clutch" facing's between the clutch pressure plate23 andthe lflywheel I9 which will result in some torquev being" transmitted' by the clutch but only su'cent "to" causethe vehicle'to possibly" move'at a creeping rate if not onanfupg'rade'i Whichlatter Condition, the Vehicle could be preventedcfrin a rollback by properly adjusting theY accelerator inan engine accelerating direction. The clutchV now begins vto picl-up'vthe'loa'don the wheels of the vehicleand asl'it picks up thisfload there will be slipping action between the' clutch faces and the ywheel surfacefand'th'e pressureplate.A Upon initial engafger'rleiit"offthe"ilywlieel'lil and the pressure plate 23- with the friction faces'A of' the yclutch disk 26',"thevVCuhioning springs 3l! will modulate as lf'rqiietiisinitted from the driving shaft throiigh'the positive-'drive lugs' H8 and H9, lie-ofthe" driven shafts' 29, IBS'. The damping springsl 3'4 thus4 serve only 'to 4cushion thedrive force applieilthroughthe clutch CL. The spring'smsbeingheavier"than the torque ratedf deectionspri'ngs |20, |.2| of they switch proper, the degree oftorque transmittal necessary to actuate the switch TS is truly.- determined by the springs' |2Q,"|2`| V'and need notA be'neces- Sarily. suhicient "to drivethe vehicle. From the foregoing lstatement` it will be, appreciated that lthe springslfido a 'functional part gezag-3 of the torque-controlling system of the present invention, inasmuch as the actuation of switch TS may be as emciently and as expeditiously carried out solely by the torque-rated springs iii), l2 i in the absence of the springs 34. Actually, the eifective functional purpose' of the illustrated springs 313 is the cushioning of the clutch elements to eliminate transferal of shock load to the vehicle drive line upon abrupt application of torque-load either by the engine or coasting drive. When the torque transmitted by the initial engaging action of the clutch reaches a degree which is sufficient to cause a yielding of the torque yielding leaf springs |29 and |2| forming a part of the torque-responsive switch TS, the shaft 29 of the clutch will have relative movement to the shaft |69 leading to the transmission and the driving lugs ||9 will be moved to engage the driving lugs I8, all as viewed in Figure 20. This will result in a closing of the torque-responsive switch TS by a placing of the contacts |26 in engagement with the contacts |33. When this switch closes the circuit including the solenoid ST will be immediately energized. When this circuit is energized the solenoid ST will also be energized and cause the plunger 92 to be shifted from the position shown in Figure 9 to the position shown in Figures 13 and 14. This movement of the plunger, upon energization of the solenoid, will immediately result in the sleeve 9|, together with t the spool valve element 19 and the rod 83, being moved to the position shown in Figure 11 wherein the forward annular flange 88 of the spool valve element will be positioned to cover the port 18. Air from the atmosphere will immediately be prevented from flowing to the chamber 56 of the servomotor M and the movement of its diaphragm Eli will be arrested, thus stopping the engaging action of the friction clutch CL. The arrested position of the diaphragm of the fluid motor and clutch elements is shown in Figure 2. The movement of the rod 83 by the plunger S2, upon energization of the solenoid ST, will result in the roller end of the rod 83 being moved out from beneath the pin |05 on the cam arm IBI, thus releasing this arm so that it can move downwardly under action of the torsional spring |06 through the slot 99, and cause its eccentric cam surface |91 to operate upon the roller IDU carried in the slot 9% at the end of the rod.

If the accelerator mechanism has been moved to such a position in speeding up the engine that the tension of the torsional spring |63 is suincient to cause movement of the rod 83 by its cam surface |01, then the rod 33 will begin to be slowly moved to the left from the position shown in Figure 1l to a position substantially that shown in Figure 13. If the torsional spring is not tensioned suiciently to cause this movement, then some additional depressing of the accelerator pedal may be necessary, but sufficient tension of the spring |06 to move rod 83 by the cam arm should be present when the accelerator has been depressed a substantial amount, as for example thirty to forty percent of its full permissible throttle travel movement thus ample power is always provided from the engine to prevent stalling upon initial engagement of the clutch by having the accelerator advancing in an engine accelerating direction with such initial engaging action.

As the spool valve element 19 is moved from the position shown in Figure 11 to the position shown in Figure 13, the port 18 will be cracked and air from the atmosphere will again be admltted through the port 18 around the forward annular ange Si) .of the spool valve element and.

then to the chamber 56 of the fluid pressure motor M. This admission of additional air under atmospheric pressure to the fluid motor will slowly tend tofurther equalize the pressures acting on the diaphragm 59 which will then gradually move rearwardly from the position shown in Figure 2 toward the position shown in Figure 3 in controlling the clutch engaging springs 25 to apply vaddition-al pressure to the pressure plate 23 and thereby clamp the clutch facings with greater intensity between the pressure plate and the flywheel. As the diaphragm moves slowly rearwardly in the iluid motor, the clutch elements will slowly assume their final engaging relation wherein the clutch engaging springs 25 exert their maximum pressurev and the clutch is considered fully engaged. The position of the diaphragm of the fluid motor M, when the clutch is fully engaged is as shown in Figure 3.

It is to be particularly noted in connection with the controlling of the re-engagement of the clutch that the rate of engagement of the final engaging movements of the clutch elements will be controlled by the extent and rate of depression of the accelerator mechanism. If it should be desired to cause the clutch to very slowly engage, following the movement of the diaphragm of the fluid motor M vbeing arrested (Figure 2), which occurs when the torque-responsive switch TS is closed (Figure 20)'and the solenoid ST energized to move the spool valve element 19 to the position shown in Figure 11, then the accelerator mechanism will be slowly opened, thus so cracking the port 18 that there Will be a slow bleeding in of air under atmospheric pressure to the chamber of the fluid motor and a correspondingly slow equalization of the pressures acting on opposite sides of the diaphragm 50 of the fluid motor M so that the diaphragm will slowly control the clutch elements into their fully engaged relation. Such an operation of the accelerator mechanism to obtain regulated full engagement of the clutch will probably be desirable when the vehicle is being started in a low speed gear from a standstill.

If it should be desired to have a quick final reengagement of the clutch after the torque-responsive switch TS is closed, then such can be obtained by a further and more rapid depressing of the accelerator mechanism so that the port 18 can be quite rapidly uncovered to its full open condition as, for example, the condition illustrated in Figure 14. Under such operations of the accelerator there will be a bleeding in of the air to the uid motor M at a greater rate of flow, thus resulting in the diaphragm 50 of the fluid motor M moving at a correspondingly greater rate of speed resulting in a faster engagement of the clutch elements.

In connection with the operation of my improved clutch controlling means, it is to be particularly noted that the extent of depressing of the accelerator mechanism will have no eifect on the rate and/or extent of re-engagement of the clutch elements at any time prior to the clutch elements reaching a point in their engagement following initial contact of the elements whereby the torque transmitted is sufficient to cause a closing of the torque-responsive switch TS. The clutch will always be controlled to engage at the same rate of movement from its fully disengaged position to a'position following initial contact of the clutch elementslirrespective of the manner declines in which the accelerator mechanism is manipulated, since this rate of engagement is always controlled by the volume of air admitted into the fiuid motor M through the port 18 which is fully open. The extent of movement to effect initial contact is out of the control of the operator after initiation of such movement, since movement to initial engagement is effected by the clutch-engaging springs 25. The extent of depressing of the accelerator mechanism, however, will always have a controlling effect on the rate of re-engagement of the clutch elements after initial engagement of the clutch elements following the closing of the torque-responsive switch TS since such extent of depressing of the accelerator mechanisms Will determine the extent of uncovering of the port 18.

It is also to be noted that with my clutch controlling mechanism the speed of the engine will always be leading the clutch engagement and thus it will Vhave sufficient power to insure that the load of the vehicle will be picked up without any stalling of the engine. This feature of my clutch control mechanism is accomplished by the torsional spring connection ibetween the accelerator mechanism and the cam arm llllwhich operates the spool valve element 'F9- controlling the volume of air'under atmospheric pressure admitted to the servornotcrY M during the re-engagement of the clutch. The torsional spring 85 is not normally so tensioned that it is capable of moving the spool valve element, but becomes so ensionedV to cause movement of said valveelement when the accelerator mechanism has been depressed a considerable extent to cause an increase in speedA of the vehicle engine. If the accelerator mechanism should be depressed cornpletely to the iioorboard during clutch re-engaging, then the torsional spring m6 will beso additionally tensioned that immediately upon the clutch transmitting sufficient torque to close the torque-responsive switch TS and causing energization of the solenoid ST, the cam arm and spool valve element i9 will immediatelyV be operated to fully uncover the port 18 sothat there will be substantially no arresting movement of the clutch elements during their initial engaging operation to full engagement. The condition of the spool valve element 'i9 during this operation is illustrated in Figure le. In this connection it is also seen that during the final movements of the accelerator mechanism to full butterfly valve open position, there will be no movement of the spool valve ie as during such movements the concentric cam surface IBB is operating on the roller SBE? at the end 'of rod 83.

t is further to be particularly noted in connection with my clutch controlling mechanism that the arresting movement of the clutch elements during engagement always occurs whenever there has been suiilcient initial contact of the elements to transmit av predetermined torque which, while not necessarily sufficientto normally drive the vehicle, may be adjusted by-varying the weight of the torque-springs i2t-l2i to cause the vehicle to creep on level terrain or to maintain the vehicle at a standstill on an upgrade with the accelerator advanced in an engineaccelerating direction to simulate the torque transmitting slip characteristics of a fluid-coupling or torqueconverter. Therefore, it can be said that arresting movement occurs at the same point during clutch engagement, irrespective of the extent of wear of the clutch` faces and'without the necessity of any/manualv orautomatic adjustmentsyas the sole factor which brings about the arresting or retardingr movement of the clutch elements in initial engaging contact is controlled solely by a predetermined torque transmitted by the clutch and this torque condition is constant irrespective of any wear of the clutch elements. Upon properly installing the control mechanism in a vehicle there will be no necessity for any maintenance adjustments and it will operate in a uniform and efficient manner throughout the service life of the clutch to give the desired smooth clutch engagement under all torque-load conditions imposed thereon. The mechanism will function to give either a fast or slow rate of final eng-agement of the clutch according to the engine controlling position of the accelerator mechanism following a ixed controlled engaging operation by torque effective after initial contact of the clutch elements notwithstanding'the-clutch faces may be new or substantially worn out.

When it is desired to disengage the clutch at any time, this is accomplished by merely Vfully releasing the accelerator pedal. This causes the cam army IBI to be returned toits position'shown in Figure 10 under a positive movement of the L- shaped lever l' dueA to the arm ilY ef said lever picking' up the cam arm i-I through the flange itil. The valve rod 83 andthe spool valvel element i9 will then be enabled toreturn t'o their positions shown in Figure 10, but this will not occur until the clutch has been disengaged' and the torque-responsive switch opened so that the solenoid ST is de-energized. The suction motor M is activated to disengage the clutch upon release of the accelerator mechanism as the released position of the mechanism will result in the switch AS- being closed and the solenoid SR energized. When such condition occurs the double valve element 78 will beplaced in the position shown in Figure l2whe'rein the intake manifold will be connected to the iluid motor M and the iluid motor disconnected from-atmosphere. When the intake manifold is connected to they fluid motor, its diaphragm will be moved forwardly to a position shown in Figure l whereinthe clutch is fully disengaged.

If the clutch CL should be disengaged, as for example when the vehicle is descending a grade and it is desired to change' the gear ratio condition of the associated gearing to a lower speed, the clutch control mechanism will nevertheless operate in the same manner as already described during re-engagement of the clutch in starting the vehicle. When it isdesired to re-engage the clutch under the aforementioned conditions, the accelerator pedal will be depressed, thus causing the valve element l!) to be placed in the position shown in Figure 15 wherein air will flow to the fluid motor M and it will-be-controlled'toregulate the clutch to initially engage under the action of the clutch engaging springs- 25. Immediately after the clutch elements initially contact, torque will begin to be transmitted through the clutch. The'direction of transmission'of torque, however, will be from the wheels of the vehicle to the engine (coasting drive') since the driven shaft IIS of the transmission will be driven by the wheels of the vehicleY atV a greater speedthan the engine crankshaft. When the torquestr-ansmitted is great enough to cause yielding ofl the torque yielding leaf springs and |'2-I, the drivingv lugs lll and H9 will engage, as shown Figure 2l, thus bringing into engagement the contact elements |30 and I2'Tto'close the torque-responsive switch TS andenergizeY the solenoid ST. The

result will be that the spool valve element 19 will be -placed in the position shown in Figure 11 so that the engaging movement of the clutch elements will be arrested and the nal engaging movements of the clutch elements to full engaged condition controlled in accordance with the eX- tent and/or rate of depressing of the accelerator mechanism in the same manner as already described. Thus it is seen that irrespective of the direction in which torque is being transmitted through the clutch after initial engagement of the clutch elements, there will always be available the same control of the clutch elements to nal engagement. By providing for the control of the clutch when torque is being transmitted therethrough in a direction toward the engine crankshaft, it will be possible to properly control the engagement of the clutch so as not to abruptly pull up the vehicle under the conditions referred to; that is, the down-shifting to a lower speed in going down a grade. By constructing the torque-responsive switch TS so that it is closed by either engine or coasting torque transmission through the clutch, a clutch controlling mechanism is obtained which will be operative under all conditions of vehicle operation. It is important to note here that clutch re-engagement following gear ratio changing during coasting drive may be accomplished without sensing the function of the torque-responsive switch, by uninterrupted accelerating movement of the pedal P.

The point during engagement of the clutch, after initial engagement of the clutch elements, at which it is desired to have the torque-responsive switch TS closed, can be varied as desired by merely changing the strength of the torque yielding leaf springs and |21. If it should be desired that the torque-responsive switch TS close almost substantially with initial contact of the clutch elements during clutch engagement, these springs will be made quite weak. If it is desired to have the clutch elements transmit, in a slipping engaged relation, a substantial amount of torque to close switch TS after they initially contact, then of course the leaf springs |20 and [2l will be made to have a greater strength.

It may be desired to have the clutch controlling mechanism embodying my invention provide for no definite arresting of the movement of the clutch elements during engagement and after they initially contact. In place of the arresting point it may be best to have merely a retarding point in the engaging movement of the clutch elements blending with continued accelerating movement of the accelerator P whenever a predetermined torque is being transmitted after initial contact of the clutch elements; that is, an establishment of a predetermined minimum rate of retardation. If this retarding is desired, it can be accomplished merely by a slight change in the construction of the spool valve element 19. The necessary change involves merely the decreasing of the width of the forward annular flange 80 of the spool valve element 19, as is shown in Figure 17 by the reference numeral 80. By decreasing the width of this flange the complete covering of the port 18 will be eliminated at the time the torque-responsive switch TS is closed. If the port 18 is never fully covered, air flowing to the chamber 56 of the suction motor M during clutch re-engagement will not be entirely stopped, but will merely be choked down; that is, establishing a minimum flow of air to the 24 fluid motor. The extent-of Achoking can 'be varied as desired by varying the width of said forward annular flange 8B of the spool valve element. When the spool valve element is caused to be moved by the accelerator through the torsional spring m6, after assuming the position shown in Figure 17, the port 'I8 will be increasingly uncovered to thus vary the rate of the final engagement of the clutch elements. With the spool valve element of Figure 17 functioning when the clutch is initially engaged, the diaphragm of the fluid motor M will not be arrested in its movement from the position shown in .Figure 1 to the position shown in Figure 3, but

will merely slow down and have a minimum rate of retardation when it reaches the point shown in Figure 2 wherein the torque-responsive switch TS is closed and the spool valve element 19 placed in the position shown in Figure 17. Whether the arresting spool valve element of Figure l1 or the retarding spool valve element of Figure 17 is employed, there nevertheless Will be a change in rate of the movement of the clutch elements toward full engaged condition at their initial engaging point. In one case the change in rate is such that there will be an arresting of the movements of the clutch elements while in the other case there will merely be a slowing down of the rate of movement of the clutch elements; but in both cases, initial engagement is followed by gradually accelerated movements to final engagement in accordance with the manipulation of the accelerator mechanism. In the controlling of the clutch control mechanism, both the arresting` and retarding functions blend into nal engaging movements which are controlled by the accelerator mechamsm.

lutch engagement is inaugurated by an operator-responsive, accelerator-actuated means through a first movement thereof; engaging movement of the clutch friction elements or members, up to establishment of a predetermined slipping torque transferal relation, is under the control of mechanism directly responsive to torque conditions within the clutch and independent of further accelerator movement; and final engaging movement of the clutch friction elements is again placed underl accelerator control movable through a second movement thereof upon actuation of the aforesaid torque-responsive mechanism to operating position. In this manner, the critical period of clutch element movement into partially engaged condition is controlled independently of vehicular operating conditions and/or accelerator manipulation following the inauguration of the clutch friction members into said partially engaged relation, while accelerator control of the overall rate of clutch engagement is maintained to suit the individual desires and driving habits of the operator. Thus, accurate and uniform clutch control to slipping and into fully engaged conditions, are always available irrespective of the extent of wear on the clutch parts or vehicular operating conditions, according to the operators mode of driving.

It will be understood that other modifications and variations will be readily apparent to those skilled in the art from the preceding description of presently preferred embodiments of the invention which are for illustrative purposes only, and it is not intended to limit the invention in its broader aspects except as set forth in one or more of the claims appended hereto: 

